This page in a nutshell: When editing, be sure to summarize your contributions.

An edit summary is a brief explanation of an edit to a Wikipedia page. When you edit a page, there is a small text entry field labeled Edit summary located under the main edit box and above the Publish changes button:

By publishing changes, you agree to the Terms of Use, and you irrevocably agree to release your contribution under the CC BY-SA 3.0 License and the GFDL. You agree that a hyperlink or URL is sufficient attribution under the Creative Commons license.

It is good practice to fill in the edit summary field, or add to it in the case of section editing, as this helps others to understand the intention of your edit. Edit summaries are displayed in lists of changes (such as page histories and watchlists), and at the top of diff pages.

Always provide an edit summary

It is considered good practice to provide a summary for every edit, especially when reverting (undoing) the actions of other editors or deleting existing text; otherwise, people may question your motives for the edit. Edits that do not have an edit summary are more likely to be reverted, because it may not be obvious what the purpose of the edit was.

Accurate summaries help other contributors decide whether it is worthwhile for them to review an edit, and to understand the change should they choose to review it. When a major edit (e.g. deletion of a substantial amount of text, a significant addition, or a substantial rewrite) doesn't have an edit summary, there are fewer reasons to assume good faith and busy editors may be more inclined to revert the change without checking it in detail. Summaries are less important for minor changes (which means generally unchallengeable changes such as spelling or grammar corrections), but a brief note like "fixed spelling" is helpful even then.

To avoid accidentally leaving edit summaries blank, you can select "Prompt me when entering a blank edit summary" on the Editing tab of your user preferences, if you have created an account.

How to write an edit summary

Summarize. Summarize the change, even if only briefly; even a short summary is better than no summary.

Explain. Give reasons for the change, if you think other editors may be unclear as to why you made it. Citing the Wikipedia policies or guidelines that you feel justified the change may be incorporated into your explanation.

Abbreviations. Abbreviations should be used with care. They can be confusing for new contributors. For an explanation of some commonly used abbreviations, see this edit summary legend.

Expand on important information. Readers who see only the summary might not get the entire picture. Prevent misunderstanding: If an edit requires more explanation than will fit in the summary box, post a comment to the article's talk page to give more information, and include "see talk" or "see discussion page" in the edit summary.

Talk pages. When editing talk pages, consider copying your comment to the edit summary, if it is brief; this allows users to check Recent changes, Page history and User contributions (see below) very efficiently.

What to avoid in edit summaries

Avoid misleading summaries. Mentioning one change but not another one can be misleading to someone who finds the other one more important. You could add something like "and misc." to cover the other changes.

Avoid vagueness. While edit summaries can be terse, they should still be specific. Providing an edit summary similar to "I made some changes" is functionally equivalent to not providing a summary at all.

Avoid inappropriate summaries. You should explain your edits, but without being overly critical or harsh when editing or reverting others' work. This may be perceived as uncivil, and cause resentment or conflict. Explain what you changed, citing the relevant policies, guidelines or principles of good writing, but do not target others in a way that may come across as a personal attack.

Use of edit summaries in disputes

Proper use of edit summaries is critical to resolving content disputes. Edit summaries should accurately and succinctly summarize the nature of the edit, especially if it could be controversial. If the edit involves reverting previous changes, it should be marked as a revert ("rv") in the edit summary.

Avoid using edit summaries to carry on debates or negotiation over the content or to express opinions of the other users involved. This creates an atmosphere where the only way to carry on discussion is to revert other editors! If you notice this happening, start a section on the talk page and place your comments there. This keeps discussions and debates away from the article page itself. For example:

Fixing

After you publish the page, you cannot change the edit summary, so be careful with it, particularly if you are in a heated content dispute – do not write things you will regret.

If you make an important omission or error in an edit summary, you can correct this by making a dummy edit (a change in the page with no visible effects), and adding further information in its own edit summary.

In the extreme case of an edit summary containing certain kinds of harmful content, the summary can be deleted on request. They may be removed from public view by administrators using Revision Deletion; such edit summaries remain visible to administrators. In even more limited circumstances the entire edit may be oversighted, leaving it and its edit summary visible only to the handful of users with the Oversight permission.

Edit summary properties and features

Limited to 250 characters. The edit summary box can hold one line of approximately 250 characters. If you attempt to type or paste more, only the first 250 or so will be displayed – the rest will be discarded. For example, attempting to add 10 new characters (at the end or in between) to a summary already containing 245 characters may result in the first 5 new characters being inserted and the second 5 being disregarded.

Show preview. The "Show preview" button also provides a preview of the edit summary to facilitate checking links.

Can't be changed after saving. After you publish the page, you cannot change the edit summary (see bugs 10105 and 13937).

Doesn't appear in searches. The built-in search function cannot search edit summaries, and they are not indexed by external search engines.

Wikilinks always rendered; other wikitext coding ignored. Edit summaries render internal links, including piped links, and interwiki links, even when enclosed within <nowiki> and </nowiki>. Therefore, copying wikitext in the edit summary box may be preferable to copying text from the preview, except when one wants to save space. Other wikitext coding is not interpreted. ~~~~ has no effect, so do not sign edit summaries.

Notes

^Use the enhanced watchlist to see all recent changes in the watched pages, not just the last change in each page.

Section editing

When adding a new section to a discussion page with the "new section" button, the section title is used as the edit summary. When editing an existing section, the section title is inserted at the beginning of the edit summary, enclosed with /* and */ marks, for example /* External links */. Details of the edit should be added after this text. In the case that you provide a long summary yourself, you can delete the section title in order to stay within the limit of 250 characters.

When viewing such an edit summary, the section name will appear in grey, with a small arrow next to it: →External links. Click the arrow to view the section (if the section no longer exists, the link will simply take you to the top of the page).

If you create a new section before or after an existing section by clicking a section "edit" link, delete the text between /* and */ marks (or change it to the new section title) to avoid confusion.[1]

^It used to be possible to manually include links to multiple sections using the /* */ syntax – this may be useful when editing several sections at once. The edit summary:

Automatic summaries

In certain circumstances, an automatic summary is generated when an edit is published without one. This is slightly different from the summary added when editing a section, as that can be modified by the user before saving.

With the exception of the automatic summary when creating a redirect, which usually says all that needs to be said, these are not a substitute for a proper edit summary – you should always leave a meaningful summary, even in the above cases. They are, however, useful in providing some context for edits made by inexperienced users who are not aware of the importance of edit summaries, and for spotting vandalism.

When starting a new thread on a talk page by using the "New section" tab, the text you type into the "subject/headline" field becomes both the heading of your discussion topic, and the edit summary for that edit.

Tags

Tags (i.e., edit tags) are brief messages that the software automatically places next to certain edits in histories, recent changes and other special pages. They are implemented by the edit filter to help assist vandalism patrollers and other page watchers. They cannot be added or removed manually.

Notes for experienced users

There are standard templates for warning editors who delete content without providing an edit summary: {{Uw-delete1}} (which assumes good faith) and {{Uw-delete2}} (which doesn't). {{Uw-editsummary}} is available for notifying users who have not provided an edit summary for other types of edit. These are available via Twinkle.

When editors stand for Adminship, their RfA pages include statistics about how often they have provided edit summaries in the past.

The 250-character limit

This section needs expansion with: instructions on how to turn off the byte counter. Please provide them. You can help by adding to it.

The limit of 250 characters is an approximation. The actual limit is 255 bytes, but it is not always possible to have an edit summary which is 255 characters long. While most everyday English characters occupy one byte each, the use of UTF-8 encoding means that some characters take up more space: the en-dash, for example, is a single character which occupies three bytes. The limit of 255 bytes includes the section title marker (and the associated /* */) and also any Wiki markup that may be present. Consider the following typical edit summary:

This is 112 bytes long: the /* History */ is 13 bytes; the – character occupies three bytes; and the [[MOS:DATERANGE|manual of style]] occupies 33 bytes. The grey figure 143 at the right is not user-entered: it indicates the number of bytes still available (255 − 112 = 143), and it changes as you type.

For editors who have JavaScript enabled, there is a script included with the page that monitors the byte-length of the summary and prevents entering summaries longer than 255 bytes (both in "Edit source" and in Visual editor). Since 18 July 2017, a count is displayed at the right-hand end of the text entry field, showing the number of unused bytes. When JavaScript is disabled, this safeguard can't function, and the only protection is the browser's limit of 255 characters, which may overflow the 255-byte limit as a result of any characters that are represented by more than one byte. When the edit is done by a bot, through an external tool (such as WP:AWB) or through some user script or gadget, it's the responsibility of the tool or script to safeguard against overflowing this limit. In any situation where more than 255 bytes are entered for the edit summary, the summary is truncated to 255 bytes[clarify] when the page is published.